Grease composition



United States Patent 3,242,077 GREASE COMPOSITION Max J. Wisotsky, University Park, Pa., and Norman R. Odell, Wappingers Falls, N.Y., assignors to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Dec. 14, 1962, Ser. No. 244,567 Claims. (Cl. 252-28) This application is a continuation-in-part application of our patent application Serial number 205,131, filed June 25, 1962, now abandoned.

The present invention relates to lubricating grease compositions having improved characteristics and, more particularly, to non-soap thickened silicon base grease compositions having improved dropping points and re-" sistance to oil bleeding.

' In commonly assigned US. 2,880,176, there are disclosed high temperature grease compositions consisting essentially of rnethylchlorophenyl silicone polymer oils thickened with a particular group of high melting point diazo compounds, namely, the dichlorobenzidine pigments commercially used in baking finishes and as rubber pigments.

It has been found that these grease compositions comprising a silicone polymer base fluid thickened with dichlorobenzidine type pigments are not always completely satisfactory in meeting high temperature requirements of Military Specification 25013C. The dropping point and oil separation values of such greases at high working temperatures fail to meet the requirements set forth in Military Specification 25013C. This specificai-ton requires the grease to exhibit a dropping point value of at least 450 F. and an oil separation value (bleeding point), after being subjected to a temperautre of 450 F. for 30 hours of not more than 7.5 percent by weight.

It has now been found that the incorporation of a thickening agent obtained by the addition of a microdimensional pyrogenic silicon dioxide to a dichlorobenzidine pigment in a particular type of oleaginous silicone polymer fluid results in unexpected advantages with respect to the oil separation values and dropping point properties of the resulting grease compositions.

In accordance with the present invention, the grease compositions comprise a chlorophenyl silicone polymer base fluid thickened with a thickening agent consisting of as one thickening component, a dichlorobenzidine compounds having the general formula C1 C1 HaC C O l CHaC O CON- wherein R is hydrogen, chlorine, methoxy or a lower alkyl group, and as the other thickening component, finely divided pyrogenic silicon dioxide.

The amounts of the composite thickening agent in the silicone polymer base fluid may vary from about 10 up to about 40 per cent by weight of the composition, the balance being the base fluid with or without added oxidation inhibitors, stringiness agents and the like.

The dichlorobenzidine pigment is the major component of the thickening agent. The dichlorobenzidine component should be present in an amount of from about 1.5 up to about 5 parts by weight of pigment per part of pyrogenic silicon dioxide. Expressed as a percentage of the grease composition, the dichlorobenzidine thickening agent component should be present in an amount between about 5 and 35 percent by weight, the pyrogenic silicon 3,24Zfl77 Patented Mar. 22, 1966 dioxide component being at least 3 percent by weight thereof, and may be up to 12 percent by weight. It is preferred that the dichlorobenzidine pigment thickening component be present in the grease in an amount between 10 and 25 percent, the balance of the thickening agent, between about 4 and 10 percent being pyrogenic silicon dioxide.

Silicone polymer grease compositions containing this composite thickening agent meet the rigid requirements for dropping point and oil separation values specified in MIL Spec. 25013C.

The dichlorobenzidine pigment component of the composite thickening agent can be prepared by diazotizing 3,3-dichlorobenzidine, such as for example, by reaction with nitrous acid in the presence of a strong acid, such as hydrochloric acid, and thereafter reacting the diazotized product with N-aryl acetoacetamide or derivative thereof having lower alkyl or chlorine substituents upon the phenyl groups as for example, by the method described in German Patent 251,479 (1912). A particularly effective dichlorobenzidine thickening component has been found to be bis (acetyl-N-o-rnethoxyphenylcarbamylmethyl)4,4'-disazo-3,3'-dichlorodiphenyl, sold under the trade name Majestic Yellow pigment by Imperial Paper and Color Co. Other dichlorobenzidine pigments, such as bis (acetyl-N-phenylcarbamylmethyl) 4,4'-d isazo3,3'dichlorodiphenyl, bis (acetyl-N-m-xylylcarbamylmethyl) 4,4'-disazo-3,3'-dichlorodiphenyl, bis ('acetyl-N-2,5-dichlorophenylcarbarnylmethyl) 4,4'-disazo-3,3'-dichlorodi phenyl and his acetyl-N-o-tolylcarbarnylmethyl) 4,4- disazo-3,3'-dichlorodiphenyl, can be used advantageously as the pigment component of the grease compositions of the present invention.

The dichlorobenzidine compounds which are employed as one of the thickening components are generally used in finely divided form, ordinarily in the form of particles below about one micron in diameter, and preferably below about 0.5 micron in diameter which may be obtained either by suitably controlling the crystallization conditions during the preparation or by fine grinding. They may be employed either in pure form or in the form of the socalled reduced toners, wherein the compounds are deposited upon particles of inert inorganic materials, such as SiO A1 0 TiO BaSO clay, etc. Generally, such inorganic materials will be present only in minor amounts, such as up to about 10 percent by weight of the thickening agent, but larger amounts up to about 25 percent by weight or higher may be present if desired. In addition, the compounds may contain small amounts, such as up to about 5 percent by weight of the thickening agent of various metal salts, particularly metal chlorides, such as zinc chloride, ferric chloride, stannic chloride, or cadmium chloride, which may enter into the crystal structure in some manner which is not entirely understood when such salts are present in the reaction mixture during the crystallization.

The grease compositions of this invention contain, as the other thickening agent component, a minor amount of microdimensional particles of a pyrogenic silicon dioxide prepared by flame hydrolysis. The pyrogenic silicon dioxide particles have an average particle diameter in the range of from about to 400 Angstroms. A pyrogenic silicon dioxide known by the trade name Cab- O-Sil has been found to be particularly etfective in the compositions of this invention. This ultrafine silicon dioxide has an average particle diameter in the range of from 150 to 250 Angstroms and a surface area of about 175 to 200 square meters per gram. The pyrogenic silicon dioxide thickening component can be used in minor amounts in the thickening agent component in the greases of the present invention, such as, from about 3 up to about 12 percent by weight, based on the weight of the composition. Excellent results can be obtained using amounts of pyrogenic silicon dioxide thickening agent component in the range of from 4 to 10 percent by weight, based on the weight of the composition.

The use of a pyrogenic silicon dioxide in amounts less than 3 percent by weight as a co-thickener with a dichlorobenzidine pigment, particularly a Majestic Yellow pigment, is not effective to impart improved high temperature dropping point and oil separation values of the greases of this invention.

The methylchlorophenyl silicones which are employed in these greases are compounds having the formula wherein R, R R R R and R are methyl, phenyl or chlorinated phenyl groups, preferably, at least, about 35 percent of such groups being methyl groups and with suflicient chlorinated phenyl groups to give a chlorine content of at least about 3 percent by weight to the polymer, and n is an integer of suflicient size to give a polymer having a viscosity in the lubricating oil viscosity range. The preferred silicone oils are those having a viscosity in the range from about 100 seconds to 600 seconds Saybolt Universal at 100 F., and containing about 4 to 12 percent by weight of chlorine. A particularly suitable material of this character is the commercial product sold under the trade name Versilube F-SO, having an average molecular weight of about 3,233, a viscosity of about 180 to 280 seconds Saybolt Universal at 100 F. and contains about 33.6 percent silica and 7.18 percent of chlorineby weight by analysis. Another suitable silicone polymer base fluid sold under the trade name Dow F-60 can be used in the grease compositions of the invention.

The methylchlorophenyl silicone polymer may be employed as the sole oil component, or it may be employed in admixture with minor amounts of other oils, particularly other synthetic oils, such as polyethers, polygiycols, diesters, polyesters or mixtures of such oils.

The grease compositions of this invention can also contain minor amounts, i.e., 0.5 to percent by weight of the composition of oxidation and corrosion inhibitors, stringiness agents, tackiness agents, lubricity agents, coloring materials and the like.

Suitable oxidation inhibitors include aryl amines, such as diphenylamine, alphaand beta-naphthlyamine, paraphenylene diamine and N,N'-diphenyl-p-phenylenediamine. Satisfactory corrosion inhibitors include, for example, lead naphthenate, sarcosine, N-acyl sarcosines and particularly N-cocoyl sarcosine.

The use of dichlorobenzidine pigments as the sole thickening agent in a silicone polymer base fluid does not provide a grease composition having satisfactory dropping point and oil separation values at high temperatures when such values are determined under the requirements of MIL Spec. 25013C. Moreover, the use of the dichlorobenzidine pigments in the form of a reduced toner, i.e, containing a minor amount of an inert organic material, such as silica or alumina as the thickening agent in silicone polymer base, oil grease compositions does not impart satisfactory high temperature dropping point and oil separation values to the resultant greases to meet the requirements of MIL Spec. 25013C for-these tests.

It is necessary to use the combination of the dichlorobenzidine pigment component with the finely divided pyrogenic silicon dioxide component to form a satisfactory thickening agent for silicone polymer greases that meet the requirements of this specification for dropping point and oil separation values.

The grease compositions of this invention can be prepared in a known manner, such as by intimately mixing the thickening agent components, a dichlorobenzidine pigment and pyrogenic silicon dioxide, with the silicone polymer base oil in a colloid mill to obtain a thorough dispersion of the pigment and pyrogenic oxide in the silicone oil. The mixing operation can be carried out at ordinary or elevated temperatures up to about 300 F. Corrosion and oxidation inhibitors can be added to the admixed composition in a conventional manner and mixing continued to produced a uniform mixture.

EXAMPLE 1 The grease was prepared by charging into a steam heated grease kettle equipped with a mechanical stirring device 150 parts of his (acetyl-N-o-methoxyphenylcarbamylmethyl) 4,4'-disazo-3,3'-dichlorodiphenyl (Majestic Yellow Pigment), 50 parts of pyrogenic silicon dioxide, sold under the trade name Cab-O-Sil, H5 grade, and 950 parts of Versilube F-SO, a methylchlorophenyl silicone polymer oil having an average molecular weight of about 3,233, and containing 33.6 percent silica and 7.18 percent chlorine on a weight basis. The ingredients were intimately mixed and milled at a temperature of 180 F. and passed twice through a Premier Colloid mill having a clearance of 0.002 inch. The resultant buttery yellow product grease had a dropping point above 500 F. and an oil separation value of 5.5 percent after being heated for 30 hours at 450 F.

EXAMPLES 2 TO 4 INCLUSIVE Following the procedure of Example 1 other grease compositions were prepared in a similar manner. The composition of these greases are shown in Table I below.

CONTROL EXAMPLE A Following the procedure of Example 1 above, a grease composition was prepared in a similar manner except that no pyrogenic silicon dioxide thickening component was present. The composition of this grease is shown in Table I below.

CONTROL EXAMPLE B Following the procedure of Example 1 above, a grease composition was prepared containing 2.6 percent pyrogenic silicon dioxide thickening component. The composition of this grease is set forth in Table 1 below. This grease was prepared to show that the use of less than 3 percent by weight of pyrogenic silicon dioxide thickening component with a dichlorobenzidine pigment was not efi'ective in providing a grease composition meeting the requirements of MIL Spec. 25013C as to dropping point and oil separation values.

Table I Control Examples Composition, Wt. Percent Majestic Yellow Pigment H-5 Cob-O-Sil Versilube F-50 Dow F-GO Z .7 Uversol Zine 3 0 Zine Naphthenate 3 Sarkosyl LC 4 C1 )Methylchlorophenylsilicone polymer, MW 3233 (33.6% 810:, 7.18%

2 Chlorinated silicone polymer, Kinematic Viscosity at F. 52.5., Pour Point below -75 F. 4.7% (31).

3 10% solution zinc naphthenate-0orrosiou Inhibitor.

4 N-cocoyl sarcosine (tree acid)-C0rrosi0n Inhibitor.

Inspection tests of the grease compositions of Table silicone polymer oil of lubricating viscosity thickened to I are shown in Table II below. a grease consistency with from about to 40 percent by Table II Control Example Tests MIL Spec.

Penetration: 1

Unworked 207 245 227 203 208 173 Worked 60 strokes 260-330 268 320 307 300 289 310 Worked Stability 10 Strokes 2 375 346 357 325 314 Dropping Point, F 3 450 447 500+ 500+ 500+ 500+ 500+ Oil Separation (Bleeding), hrs.,

450 F., Percent Loss 2 7. 5 8. 7 9. 9 5. 5 l. 4 2. 2 0. 6 High Temperature Performance, hrs.

to failure at 450 F 3 500 747 Dynamic Water Resistance Test,

Percent Loss 2 5. O 0 0 0 0 Oil Evaporation Test, 22 hrs., 400

F., Percent Loss 2 4 3. 9 4. 0

ASTM Bomb Oxidation Test, 100

hrs., 250 F., lbs. Drop 2 0 Copper Strip Corrosion Test, 24 hrs.,

212 F., rating 1 Converted to ASTM from $4 cone, worker used.

2 Maximum.

3 Minimum.

4 Pass.

The data in Table II above, Example A, show that weight of a thickening agent consisting of a mixture of the dropping point and oil separation values of a grease a finely divided pyrogenic silicon dioxide and a dichlorocomposition comprising a chlorophenyl silicone polymer benzidine pigment having the formula Cl Cl HaC (I) O I l s I 0 R Q-noo CHN- H H base fluid containing only a thickening agent of dichlorof f R represents a membFr selected from the group benzidine pigment, Majestic Yellow, but without any conslstmg of hydrogen, chlonlleg h lower pyrogenic silicon dioxide, does not meet the requirements alkyl, P sald P g belng P set forth in MIL Spec. 25013Cfor these values. The data ent 1n e 60111130310011 1n Wglght g p presented in Table II above, for Example B, illustrate tlmeF Pf P by Welghi 0f 531d 51116011 dlOXld6, that the use of an amount f less than 3 percent by said SlllCOIl dioxide being present in an amount between 3 weight of pyrogenic silicon dioxide thickening compoand lzpercent by m; nent with a dichlorobenzidine pigment thickening comgflease composltlon' as f c1a 1m 1 Where ponent in a silicone polymer grease is likewise unsatsald slhcone Polymer 011 a Vlscoslty 111 f range i f t when determined by MIL Spec 25013C with of from about 100 to 600 seconds Saybolt Universal at respect to the dropping point and oil separation values. 9 and cfmtams between about 4 12 Percent by The data set forth for the grease compositions of EX- Welght of Chlonneamples 1 to 4 inclusive in the table, illustrate that grease gr ease COmPQS1PIOH as clalmed clfilm 1 Where compositions containing from 3 to 8 percent by weight In said dichlorobenzidine component 1s b1s(acetyl-N-omethoxyphen'ylcarbamylmethyl) 4,4i'-disazo-3 ,3 '-dichlorotdiphenyl.

4. A grease composition as claimed in claim 1, wherein said dichlorobenzidine component is bis(acetyl-n-phenylcarbamylmethyl) 4,4'-disazo-3 ,3 '-dichlorodiphenyl.

5. A grease composition as claimed in claim 1, Wherein said dichlorobenzidine component is bis(acetyl-n-mxylylcarbamylmethyl)4,4'-disazo-3,3'-dichlorodiphenyl.

of pyrogenic silicon dioxide possess dropping point and oil separation values Within the requirements of MIL Spec. 250130. These examples show that the grease composi- 60 tions of the present invention, namely, grease compositions containing at least 3 percent by weight of a pyrogenic silicon dioxide thickening component with a dichlorobenzidine pigment in a chlorophenyl silicone polymer base thickening component are Superior as to their pp 6. A grease composition as claimed in claim 1, wherepoint and oil separation values in comparison with silicone i id di hl b idi Component i bj 1-N-2 5 grease compositions containing less than 3 percent pyro-- dichlorophenylcarbarnylmethyl)4,4'-disazo-3,3' dichlor genic silicon dioxide thickening component, and a didiphenyl. chlorobenzidine thickening component or greases con- 7. A grease composition as claimed in claim 1, wheret-ainxing no pyrrogenic silicon dioxide thickening compoin said dichlorobenzidine component is bis(acetyl-N-onent. tolylcarbamylmethyl)4,4'disazo-3,3-dichlorodiphenyl.

We claim: 8. A grease composition as claimed in claim 1 where- 1. A lubricating grease composition comprising from in said pyrogenic silicon dioxide component of said thickabout 60 to percent by weight of a methylchlorophenyl 75 ening agent has an average particle size of about to '5 8 250 A. and a surface area of about 175 to 200 meters References Cited by the Examiner g i m s 1 d in 1 1 con UNITED STATES PATENTS grease c post ion a c aime c an taining about 0.5 percent by Weight of a corrosion in- 2880176 3/1959 Roiilch et a1 252 496 3,037,933 6/1962 Wright 252-28 hlbitor and about 0.5 percent of an oxldation 1nh1b1tor, 5 3 102 860 9/1963 Zakin 252 28 nawe1ght basls' 3,102,861 9/1963 Zakin 252-28 10. A grease composltion as claimed in 012mm 1 con- 3 126 341 3/1964 Zakin sisting essentially of from 65 to 86 percent of said silicone polymer oil, 10 to about 25 percent of bis(acetyl-N- FOREIGN PATENTS o-methoxyphenylcarbamylrnethy )4,4'-disazo-3,3'-dich1o- 10 846.647 8/1960 Great Britain.

rodiphenyl and from about 4 to about 10 percent of finely divided pyrogenic silicon dioxide, on a weight basis. DANIEL WYMAN, Primary Examine"- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 242 ,077 March 22 1966 Max J. Wisotsky et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4 line 16, for "produced" read product same column 4, Table I, second column, line 1 thereof, for "200" read 20 column 6, lines 37 to 43, the right-hand portion of the formula should appear as shown below instead of as in the patent:

CH3CO R N=N- H same column 6, lines 61 and 64, for "bis(acetyln-", each occurrence, read bis(acety1-N Signed and sealed this 15th day of August 1967.

(SEAL) Attest:

EDWARD M. FLETCHER,JR. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A LUBRICATING GREASE COMPOSITION COMPRISING FROM ABOUT 60 TO 90 PERCENT BY WEIGHT OF A METHYLCHLOROPHENYL SILICONE POLYMER OIL OF LUBRICATING VISCOSITY THICKENED TO A GREASE CONSISTENCY WITH FROM ABOUT 10 TO 40 PERCENT BY WEIGHT OF A THICKENING AGENT CONSISTING OF A MIXTURE OF A FINELY DIVIDED PYROGENIC SILICON DIOXIDE AND A DICHLOROBENZIDINE PIGMENT HAVING THE FORMULA 